Screw



(No Mode1 J. P. A. HANLON,

SCREW. No. 379,200. Patented Mar. 6,1888.

llllll UNITED STATES PATENT OFFICE.

JOSEPH P. A. HANLON, OF SOMERVILLE, ASSIGNOR OF ONE-SEVENTH TO CHARLES A. DAVID, OF LYNN, MASSACHUSETTS.

SCREW.

SPECIFICATION forming part of Letters Patent No. 3791200, dated March 6, 1888.

Application filed November 18, 1887. Serial No. 255,458. (No model.)'

To all whom, it may concern:

Be it known that I, J OSEPH P. AJHANLON, a citizen of Great Britain, and a resident of Somerville, in the county of Middlesex and State of Massachusetts, haveinvented new and useful Improvements in Screws, of which the following, taken in connection with the accompanying drawings, is a specification.

This invention relates to improvements in screws; and it consists in an improvement in the nick of the head so as to prevent the screwdriver from accidentally slipping out of said nick during the operation of turning the screw in or out of the materialinto which it is to be secured.

The invention is carried out as follows, reference being had to the accompanying drawings, wherein- Figure 1 represents a side elevation of a screw made according to my invention. Fig. 2 represents a central longitudinal section of the head and shank of the same. Figs. 3 and 4 represent plan views of the screw-heads, showing the i mproved nicks therein; and Figs. 5 and 6 represent end views. of screw-drivers used in driving the improved screws.

Similar letters refer to similar parts wherever they occur on the different parts of the drawings.

a is the screw-shank, having a machine or wood thread out on it, as usual.

b is the head, as usual, in the upper end of the shank a, which head may be made of any of the ordinary formsthat is, cylindrical, semispherical, or tapering-accordingto the uses for which the screw is intended, and I wish to state that I do not desire to confine myself to any particular shape of the head, as this may be varied according to circumstances.

0 in the drawings is the nick in the head, which is made of the usual depth, but instead of being straight, as is common in ordinary screws, it is made serpentine or zigzag from end to end, as shown, respectively, in Figs. 3 and 4. WVith such improved nick I use a screw-driver the lower end of which is made serpentine or zigzag shaped to correspond with the nick in the screw-heads, as shown in Figs. 5 and 6, and by this arrangement the liability of thescrew driver slipping accidentally out of the nick while the screw is being driven or removed is entirely obviated.

The bottom of the nick c is on .a plane at a right angle to the axis of the screw without 

